Tag: 2017

cs193p – Assignment #1 Task #3

Add some more operations buttons to your calculator such that it has at least a dozen operations total (it can have even more if you like). You can choose whatever operations appeal to you. The buttons must arrange themselves nicely in portrait and landscape modes on all iPhone 6’s and 7’s.

Start adding the new operations to the brain model:

    private let operations: Dictionary<String,Operation> = [
        ...        
        "x²" : Operation.unaryOperation({ pow($0, 2) }),
        "x³" : Operation.unaryOperation({ pow($0, 3) }),
        "x⁻¹" : Operation.unaryOperation({ 1 / $0 }),
        "sin" : Operation.unaryOperation(sin),
        "tan" : Operation.unaryOperation(tan),
        "sinh" : Operation.unaryOperation(sinh),
        "cosh" : Operation.unaryOperation(cosh),
        "tanh" : Operation.unaryOperation(tanh),
        "ln" : Operation.unaryOperation(log),
        "log" : Operation.unaryOperation(log10),
        "eˣ" : Operation.unaryOperation(exp),
        "10ˣ" : Operation.unaryOperation({ pow(10, $0) }),
        "x!" : Operation.unaryOperation(factorial),
        "xʸ" : Operation.binaryOperation(pow),
        ]

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cs193p – Assignment #1 Task #2

Your Calculator already works with floating point numbers (e.g. if you touch 3 ÷ 4 =, it will properly show 0.75), however, there is no way for the user to enter a floating point number directly. Fix this by allowing legal floating point numbers to be entered (e.g. “192.168.0.1” is not a legal floating point number!). You will need to have a “.” button in your calculator. Don’t worry too much about precision or significant digits in this assignment (doing so is Extra Credit).

… the button has already been added during the lecture. Because it has been copied from a digit button it points already to touchDigit. When the user is in the middle of typing, only add the digit if it is not a “.”, or if there is not already one on the display. For new new numbers, add a leading zero if necessary: 

    @IBAction func touchDigit(_ sender: UIButton) {
        ...
        if userIsInTheMiddleOfTyping {
            ...
            if "." != digit || !textCurrentlyInDisplay.contains(".") {
                display.text = textCurrentlyInDisplay + digit
            }
        } else {
            display.text = "." == digit ? "0." : digit
            ...
        }        
    }

As requested in the hints we added only a single line, and adjusted another one.

The complete code for the assignment #1 task #2 is available on GitHub.

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